Allow Control+Shift+Q on lock screen.

ash/accelerators/accelerator_table.cc

Index: ash/accelerators/accelerator_table.cc
diff --git a/ash/accelerators/accelerator_table.cc b/ash/accelerators/accelerator_table.cc
index 225ad90b49f256a19176212baa9fbfd8502a9352..0800a90c12a665d8571e24308d9077aaba1982da 100644
--- a/ash/accelerators/accelerator_table.cc
+++ b/ash/accelerators/accelerator_table.cc
@@ -128,7 +128,7 @@ const AcceleratorData kAcceleratorData[] = {
 
 const size_t kAcceleratorDataLength = arraysize(kAcceleratorData);
 
-const AcceleratorAction kActionsAllowedAtLoginScreen[] = {
+const AcceleratorAction kActionsAllowedAtLoginOrLockScreen[] = {
   BRIGHTNESS_DOWN,
   BRIGHTNESS_UP,
   NEXT_IME,
@@ -149,7 +149,14 @@ const AcceleratorAction kActionsAllowedAtLoginScreen[] = {
 #endif
 };
 
-const size_t kActionsAllowedAtLoginScreenLength =
-    arraysize(kActionsAllowedAtLoginScreen);
+const size_t kActionsAllowedAtLoginOrLockScreenLength =
+    arraysize(kActionsAllowedAtLoginOrLockScreen);
+
+const AcceleratorAction kActionsAllowedAtLockScreen[] = {
+  EXIT,
+};
+
+const size_t kActionsAllowedAtLockScreenLength =
+    arraysize(kActionsAllowedAtLockScreen);
 
 }  // namespace ash